Airbags were an option on VS models. If an airbag was originally fitted to the vehicle and someone removed it, then its probably still got its SRS module-(crash sensor) fitted. Check under the drivers seat on the floor, and if theres no black metal box under there, then it could be that the the vehicle was never fitted with airbags, or that the module has been removed too, in which case it would have left a square hole in the carpet under there.. If the module is there, then you will have to fit an airbag equipped steering wheel to the vehicle and refit the SRS dashlight bulb, which should come on when the igntion key is turned to the ON position, and either stay on if theres a fault detected in the SRS systems, or go off after 3.5 seconds if no faults are detected in the SRS systems..
You can also check the option codes, if a VR or VS was originally fitted with drivers side airbag, then the build plate (i think its on the build plate) should show option code AJ3-" Drivers restraint inflatable". Some people have found the build sheet for their vehicle under the front passenger side carpet, and this paper shows all the build options for that vehicle, a very handy thing to have, especially in your case.
You could probably also phone holden, have the VIN handy, and they should be able to tell you what factory options were fitted to that vehicle.